Changes in brain activity during language learning in adults measured by magnetoencephalography

278 p.The main goal of this thesis was to characterize language-related short-term learning changes in the adult brain. Previous studies have mainly used longitudinal and cross-sectional designs and therefore they captured brain responses of already consolidated rules. On the other hand, studies that used on line or lab training, and therefore captured short-term changes, were conducted in EEG and provided no source correlates related to these changes. However, short-term and long-term learning seem to elicit different plastic changes hence, the anatomical-correlates of the MEG experiments carried out in this thesis would provide useful information to better understand which plastic changes occur in short-term learning. Subsets of natural languages (miniature languages) were used in two of the experiments in order to study short-term changes. It was hypothesized that miniature languages allow to capture language-related changes without the need of course-like long-lasting training. The third experiment was a memory task in participants' native language, and aimed to provide a better understanding of physiological memory functions, especially the role of oscillations in memory retrieval. Therefore, this thesis opens a door to a new way of studying L2 learning, providing anatomical correlates of short-term language related brain changes.Basque Center on Cognition Brain and Languag

Changes in brain activity during language learning in adults measured by magnetoencephalography

278 p.The main goal of this thesis was to characterize language-related short-term learning changes in the adult brain. Previous studies have mainly used longitudinal and cross-sectional designs and therefore they captured brain responses of already consolidated rules. On the other hand, studies that used on line or lab training, and therefore captured short-term changes, were conducted in EEG and provided no source correlates related to these changes. However, short-term and long-term learning seem to elicit different plastic changes hence, the anatomical-correlates of the MEG experiments carried out in this thesis would provide useful information to better understand which plastic changes occur in short-term learning. Subsets of natural languages (miniature languages) were used in two of the experiments in order to study short-term changes. It was hypothesized that miniature languages allow to capture language-related changes without the need of course-like long-lasting training. The third experiment was a memory task in participants' native language, and aimed to provide a better understanding of physiological memory functions, especially the role of oscillations in memory retrieval. Therefore, this thesis opens a door to a new way of studying L2 learning, providing anatomical correlates of short-term language related brain changes.Basque Center on Cognition Brain and Languag

Closing eyes during auditory memory retrieval modulates alpha rhythm but does not alter tau rhythm

Available online 20 April 2019The alpha power increase that occurs when the eyes are closed is one of the most well-known effects in human electrophysiology. In particular, previous psychological studies have investigated whether eye closure can boost memory performance under certain circumstances, providing contradictory evidence across sensory input modalities. Although alpha power is modulated during different phases of memory and these modulations are correlated with performance, few studies have reported on the relationship between eye closure, memory, and alpha-band power. The present study investigates the influence of eye closure while participants (n = 21) performed an auditory recognition memory task with spoken words during the recording of magnetoencephalography (MEG) data. Our results showed no evidence for a behavioural effect of eye closure in the performance of the task. In addition, electrophysiological responses to the stimuli showed the expected alpha event-related desynchronization (ERD) 0.5–1 s and a high-alpha/beta event-related synchronization (ERS) 1–2 s after word onset. The data showed the expected memory effect, i.e. remembered words elicited greater 10 Hz ERD than forgotten words in the brain regions typically associated with the language network, suggesting a modulation of tau rhythm. Eye closure modulated alpha rhythm only in posterior-parietal and occipital regions. The lack of interaction and the different localizations found for modulations of tau and classical alpha rhythms suggests that these rhythms play distinct functional roles in memory performance.This research was possible thanks to the support of the “Severo Ochoa Program for Centres/Units of Excellence in R&D” (SEV-2015-490). AB was supported by the Basque Government (Eusko Jaurlaritza) under the program “Ikertzaile ez doktoreen doktoretza-aurreko formakuntza programa” ( PRE_2015_2_0208), CCG was supported by the Spanish Ministry of Economy and Competitiveness through the Juan de la Cierva (IJCI- 2014-20821) and Ramon y Cajal (RYC-2017-21845) Fellowships

An Event Related Field Study of Rapid Grammatical Plasticity in Adult Second-Language Learners

Published: 24 January 2017The present study used magnetoencephalography (MEG) to investigate how Spanish adult learners of Basque respond to morphosyntactic violations after a short period of training on a small fragment of Basque grammar. Participants (n = 17) were exposed to violation and control phrases in three phases (pretest, training, generalization-test). In each phase participants listened to short Basque phrases and they judged whether they were correct or incorrect. During the pre-test and generalization-test, participants did not receive any feedback. During the training blocks feedback was provided after each response. We also ran two Spanish control blocks before and after training. We analyzed the event-related magnetic- field (ERF) recorded in response to a critical word during all three phases. In the pretest, classification was below chance and we found no electrophysiological differences between violation and control stimuli. Then participants were explicitly taught a Basque grammar rule. From the first training block participants were able to correctly classify control and violation stimuli and an evoked violation response was present. Although the timing of the electrophysiological responses matched participants' L1 effect, the effect size was smaller for L2 and the topographical distribution differed from the L1. While the L1 effect was bilaterally distributed on the auditory sensors, the L2 effect was present at right frontal sensors. During training blocks two and three, the violation-control effect size increased and the topography evolved to a more L1-like pattern. Moreover, this pattern was maintained in the generalization test. We conclude that rapid changes in neuronal responses can be observed in adult learners of a simple morphosyntactic rule, and that native-like responses can be achieved at least in small fragments of second language.Support for this project was provided to DD by Spanish Ministry of Science and Innovation (MICINN) under the program “Plan Nacional” (grant reference PSI 2011-24802) and to AB by the Basque Government (Eusko Jaurlaritza) under the program “Ikertzaile ez doktoreen doktoretza-aurreko formakuntza-programa” (grant reference PRE_2015_2_0208)

Development of a Sentinel-2 burned area algorithm: Generation of a small fire database for sub-Saharan Africa

A locally-adapted multitemporal two-phase burned area (BA) algorithm has been developed using as inputs Sentinel-2 MSI reflectance measurements in the short and near infrared wavebands plus the active fires detected by Terra and Aqua MODIS sensors. An initial burned area map is created in the first step, from which tile dependent statistics are extracted for the second step. The whole Sub-Saharan Africa (around 25 M km(2)) was processed with this algorithm at a spatial resolution of 20 m, from January to December 2016. This period covers two half fire seasons on the Northern Hemisphere and an entire fire season in the South. The area was selected as existing BA products account it to include around 70% of global BA. Validation of this product was based on a two-stage stratified random sampling of Landsat multitemporal images. Higher accuracy values than existing global BA products were observed, with Dice coefficient of 77% and omission and commission errors of 26.5% and 19.3% respectively. The standard NASA BA product (MCD64A1 c6) showed a similar commission error (20.4%), but much higher omission errors (59.6%), with a lower Dice coefficient (53.6%). The BA algorithm was processed over > 11,000 Sentinel-2 images to create a database that would also include small fires (< 100 ha). This is the first time a continental BA product is generated from medium resolution sensors (spatial resolution = 20 m), showing their operational potential for improving our current understanding of global fire impacts. Total BA estimated from our product was 4.9 M km(2), around 80% larger area than what the NASA BA product (MCD64A1 c6) detected in the same period (2.7 M km(2)). The main differences between the two products were found in regions where small fires (< 100 ha) account for a significant proportion of total BA, as global products based on coarse pixel sizes (500 m for MCD64A1) unlikely detect them. On the negative side, Sentinel-2 based products have lower temporal resolution and consequently are more affected by cloud/cloud shadows and have less temporal reporting accuracy than global BA products. The product derived from S2 imagery would greatly contribute to better understanding the impacts of small fires in global fire regimes, particularly in tropical regions, where such fires are frequent. This product is named FireCCISFD11 and it is publicly available at: https://www.esa-fire-cci.org/node/262, last accessed on November 2018.This research was carried out within the Fire_cci project (https://www.esa-fire-cci.org/, last accessed on November 2018), contract no. 4000115006/15/I-NB, which has been funded by the European Space Agency (ESA) under the Climate Change Initiative Programme. The FireCCISFD11 product can be downloaded at https://www.esa-fire-cci.org/node/262 (last accessed on November 2018)

Changes in brain activity during language learning in adults measured by magnetoencephalography

278 p.The main goal of this thesis was to characterize language-related short-term learning changes in the adult brain. Previous studies have mainly used longitudinal and cross-sectional designs and therefore they captured brain responses of already consolidated rules. On the other hand, studies that used on line or lab training, and therefore captured short-term changes, were conducted in EEG and provided no source correlates related to these changes. However, short-term and long-term learning seem to elicit different plastic changes hence, the anatomical-correlates of the MEG experiments carried out in this thesis would provide useful information to better understand which plastic changes occur in short-term learning. Subsets of natural languages (miniature languages) were used in two of the experiments in order to study short-term changes. It was hypothesized that miniature languages allow to capture language-related changes without the need of course-like long-lasting training. The third experiment was a memory task in participants' native language, and aimed to provide a better understanding of physiological memory functions, especially the role of oscillations in memory retrieval. Therefore, this thesis opens a door to a new way of studying L2 learning, providing anatomical correlates of short-term language related brain changes.Basque Center on Cognition Brain and Languag

Development of a Sentinel-2 burned area algorithm: Generation of a small fire database for sub-Saharan Africa

A locally-adapted multitemporal two-phase burned area (BA) algorithm has been developed using as inputs Sentinel-2 MSI reflectance measurements in the short and near infrared wavebands plus the active fires detected by Terra and Aqua MODIS sensors. An initial burned area map is created in the first step, from which tile dependent statistics are extracted for the second step. The whole Sub-Saharan Africa (around 25 M km(2)) was processed with this algorithm at a spatial resolution of 20 m, from January to December 2016. This period covers two half fire seasons on the Northern Hemisphere and an entire fire season in the South. The area was selected as existing BA products account it to include around 70% of global BA. Validation of this product was based on a two-stage stratified random sampling of Landsat multitemporal images. Higher accuracy values than existing global BA products were observed, with Dice coefficient of 77% and omission and commission errors of 26.5% and 19.3% respectively. The standard NASA BA product (MCD64A1 c6) showed a similar commission error (20.4%), but much higher omission errors (59.6%), with a lower Dice coefficient (53.6%). The BA algorithm was processed over > 11,000 Sentinel-2 images to create a database that would also include small fires (< 100 ha). This is the first time a continental BA product is generated from medium resolution sensors (spatial resolution = 20 m), showing their operational potential for improving our current understanding of global fire impacts. Total BA estimated from our product was 4.9 M km(2), around 80% larger area than what the NASA BA product (MCD64A1 c6) detected in the same period (2.7 M km(2)). The main differences between the two products were found in regions where small fires (< 100 ha) account for a significant proportion of total BA, as global products based on coarse pixel sizes (500 m for MCD64A1) unlikely detect them. On the negative side, Sentinel-2 based products have lower temporal resolution and consequently are more affected by cloud/cloud shadows and have less temporal reporting accuracy than global BA products. The product derived from S2 imagery would greatly contribute to better understanding the impacts of small fires in global fire regimes, particularly in tropical regions, where such fires are frequent. This product is named FireCCISFD11 and it is publicly available at: https://www.esa-fire-cci.org/node/262, last accessed on November 2018.This research was carried out within the Fire_cci project (https://www.esa-fire-cci.org/, last accessed on November 2018), contract no. 4000115006/15/I-NB, which has been funded by the European Space Agency (ESA) under the Climate Change Initiative Programme. The FireCCISFD11 product can be downloaded at https://www.esa-fire-cci.org/node/262 (last accessed on November 2018)